Page:Popular Science Monthly Volume 43.djvu/115

Rh class of the two, the butter dairyman can only afford to keep profitable cows, and the thousands of creameries over the country can not afford to purchase good and poor milk for one and the same price, for that is unjust to the person supplying the best grade of milk. Consequently, for some years chemists have been laboring to invent some simple method of determining the percentage of fat in milk, so that creamery men and farmers with a common education might be able to use it, and thus test their milk accurately. The first method for practical application among farmers to attract very general attention was that devised by Mr. F. G. Short, chemist to the Wisconsin Experiment Station, whose method was published in 1888. This, however, was somewhat complex, and too slow of operation. Other methods were afterward developed by Messrs. Patrick, Parsons, Cochran, Babcock, etc. Dr. S. M. Babcock, while chemist at the New York State Experiment Station, did much valuable work in the study of milk and its products, and in 1889, after becoming chemist of the State Experiment Station at Madison, Wis., he developed and brought out a method for testing the fat in milk or cream that is now a recognized success. The method is simple, and can easily be performed by any person of fair intelligence. Equal quantities of milk and sulphuric acid are placed in specially constructed bottles, and these put in a simple machine, largely consisting of a tin cylinder or wheel, about fifteen or twenty inches in diameter, revolving on its side, within which, after the manner of spokes, are cups or pockets, in which these bottles are placed. The wheel is revolved by a crank and cog movement, and by centrifugal force and the action of the acid the fat in the milk is separated from the rest of the fluid. Enough hot water is added to each bottle to fill the measuring neck, and the fat, after five or six minutes' turning of the machine, comes to the top clear and yellow, after which the amount present may be read upon the graduated lines on the sides of the long neck of the bottle. The milk of as many as twenty-four cows can be tested in an hour. Machines of from four to fifty bottles capacity are manufactured.

This invention, the result of long and laborious scientific research, is not patented, and is largely used in the creameries of Wisconsin, Iowa, Illinois, and many other States in the purchasing of milk. The patrons of the creameries are paid for their milk according to its quality, as decided by the Babcock machine. Such a method as this is a blessing to the country, for it informs the farmer if his milk is inferior to that of his neighbor, and will consequently incite him to improve his stock.